| This dissertation is concerned with studies on the performance aspects of mobile LEO satellite cellular systems. Relevant performance measures studied in the dissertation include new call blocking probability, handoff failure probability, call termination probability, and call dropping probability. The analytical teletraffic models available in the literature are generalized in this work in order to characterize the 3G systems more realistically. The effect of earth rotation on cell residence time is also investigated and a new cell residence time model is developed. The new model proposed uses right-truncated gamma distribution to describe the statistics of residence time in the origination cell; and, the generalized beta distribution is used to model the residence time in subsequent cells.; A closed-form expression to determine the premature call termination and call dropping probabilities is proposed. The proposed expression requires only the cumulative distribution function of the call holding time and the first four moments of the cell residence time. In all the above probabilistic considerations, the arrival process is regarded as: (i) Poissonian implying voice-like traffic and (ii) non-Poissonian depicting inhomogeneous mix of voice, data, and video transmissions expected on a trunk traffic.; The effect of factors that may affect the signal intensity on the performance of mobile LEO satellite cellular systems is also investigated. In particular, a mathematically tractable expression to approximate the moments of cell residence time in origination cell as well as in subsequent cells is developed based on the received signal power. |
